The system and method of fluctuation enhanced gas-sensing using SAW devices generally relates to chemical analyte detection and identification, and more particularly, to a system and method of chemical analyte detection and identification by analysis of frequency fluctuations in a chemical sensor arranged to produce an oscillatory output signal when exposed to chemical substances.
Homeland defense, including anti-terrorist efforts require highly selective, sensitive, and reliable detection of harmful agents. Intensive research has resulted in the use of chemical and biological sensor elements for the development of systems known as electronic noses (for gas and odor sensing) and electronic tongues (for fluid sensing).
Presently available electronic noses and tongues are most commonly based on the measurement of conductance or the electrochemical potential of surface-active devices. Such noses and tongues are not sufficiently reliable, selective, nor sensitive for certain applications. In addition, these sensor components have high false alarm rates and short lifetimes.
A more sensitive and reliable way of gas sensing is based on surface acoustic wave (SAW) devices. These devices generally operate by measuring the propagation velocity of acoustic waves between electrode pairs. As gas molecules are adsorbed by the SAW device the mass of the SAW device is increased, thereby reducing the propagation velocity between the electrode pairs. Traditionally, only the average resonant frequency of the propagating wave is measured and microfluctuations of the instantaneous frequency are ignored. This method of only measuring average resonant frequency is not selective (only the adsorbed mass is measured) and is highly susceptible to inaccuracies due to changes in temperature.
Therefore, it can be appreciated that a highly selective, sensitive, and reliable method of gas-sensing that is less susceptible to inaccuracies due to changes in temperature is needed.